biomass train. The feeds to the biomass train are one of two types: Raw biomass Partially upgraded biomass via pyrolysis or HTL processes (wood waste and algae) The upgrading systems may be located near the source of the biomass. The biofuels train consists of a hydroprocessing unit to saturate the olefins and remove the remaining oxygen. The second stage saturates the aromatics as required to allow hydrocracking into the desired streams. Hydroprocessing does not change the chain length of the carbons or the aromatic side chains. Therefore, an additional hydroprocessing step will likely be required to modify the molecular structure to meet cold flow property specifications for jet fuel and diesel. train allows utilisation of the existing refining equipment. In this configuration, the first unit saturates and produces feeds for processing in existing units. Due to the exothermic nature of the resulting product, some derating of the existing equipment occurs. The result is a lower yield of final products. The expectation is that the processing selection of the bio-train meets the Integrated system Integration of the biofuels into the fossil requirements for the fossil train. For example, some of the biofeed might be suitable for directly charging to the FCC unit (Huber, et al ., 2007), (Melero, et al., 2012). Once processed, the resulting FCC distillate products can be charged to the hydrocracker or diesel hydrotreater and the naphtha range products
+
–
O + 4H + 4e + –
2H O
4H + 4e
2H
+ Anode
Cathode
–
Oxygen
Hydrogen
Membrane
Figure 4 Electrolytic hydrogen
can require specialised heating systems to manage reasonable flow rates of waxy renewable feeds. For significant processing levels of renewable feeds, truck delivery will require multiple unloading bays/locations and specific setups for quality control testing/segregation. Scenarios and emissions The different future refinery will operate with clean fuels utilities and no/limited carbon-fired sources. Feeds to the biorefineries will be from non-food sources and require upgrading in the liquid scenarios. The final scenario utilises gasification of the biomass and Fisher-Tropsch to convert the syngas into liquid fuels or other products (Yanez, et al ., 2020), (Kargbo, et al., 2021), (Freeman, et al., 2013), (Hart, et al., 2021), (Dhar, et al. , 2018). Separate trains The separate train scenario utilises the existing refinery assets and augments them with a new
A. Separate fossil & biomass trains
B. Integrated system
C. Fossil train with biomass gasification
Fossil train
Crude
Products
Fossil train
Fossil train
Crude
Products
Crude
Products
Biofuels gasi cation & Fischer - Tropsch train
Biofuels train
Products
Biomass
Products
Biomass
Biofuels train
Biomass
Figure 5a Separate fossil and biomass trains 5b Integrated system 5c Fossil train with biomass gasification
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